A recent report from Morbidity and Mortality Weekly Report (MMWR) from the U.S. Centers for Disease Control and Prevention (CDC) shows just how easily and quickly SARS-CoV-2, the virus that causes COVID-19, can spread.

In the May 12 report, researchers looked at information from a March 10 choir practice in Skagit County, Washington, which had 61 people in attendance, including one symptomatic person. After the group practice with just one symptomatic person, 52 of the 61 people in attendance had symptoms of COVID-19 (32 of them were confirmed cases and 20 were probable secondary COVID-19 cases). Of the 53 people who were ill, three people were hospitalized, and two people died.

The report noted that choir practice presents opportunities for transmission, such as sitting close to other choir members, sharing snacks and stacking chairs together at the end of practice. The researchers also note that singing itself can be an opportunity for transmission, through the emission of aerosols it causes, and that certain people called superemitters can release more aerosol particles during speech than others, which could contribute to cases of COVID-19 superspreading.

The data highlight how quickly SARS-CoV-2 can spread and the possibility of superemitters who can contribute to a COVID-19 superspreading event. The researchers recommend maintaining social distancing measures like staying at least six feet apart from others, not gathering in groups and wearing cloth face coverings in public where social distancing measures can be hard to maintain.

Read the full report.